General account of lichens ppt 23.02.2021

About lichen, its definition, basic growth form with figure, on the basis of substrate growth form, importance

1. General account of Lichens
Dr. ShobhaRawat
(MSc Botany, Ph. D.)
Botany Department
Assistant Professor (T. P.)
Department of Botany
SobanSingh JeenaUniversity, Almora

2. Whatare Lichens?
Lichens are fungi that live in intimate
symbiotic association with green algae or cyanobacteria.
x10

3. Lichenisacompositeorganismthatis
formedbyasymbioticrelationship
betweenalgaeorcyanobacteriaandsome
fungispecies.
or
Anycomplexorganismofthegroup
Lichens,composedofafungusin
symbioticunionwithanalgaandhavinga
greenish,gray,yellow,brown,orblackish
thallusthatgrowsinleaflike,crustlike,or
branchingformsonrocks,trees.
Example: Lecanora, Parmelia,
Flavoparmelia
•Lichen Definition

4. Thepeculiarstructureanduniquephysiologyoflichens
enablethemtocolonizeonanumberofsubstratesin
variedclimaticcondition.
Lichenshaveanabilitythattheycangrowonasubstrate
whichisnotcolonizedbyothergroupofplant,suchas
glass,bone,manmadeartifactsandbarrenrocks.
LichengrowinextremeconditionliketheArctic,Tundra,
hotspot,hotdrydesert,rockycoaststoxicheapsroof,
roofbarerocks,walls,exposedsoilsurface.
Lichenoccurfromhighalpineelevationtosealevelthe
abilitytogrowanysurface.
Morethan50%ofthelichensubstanceshaveantibiotic
activity.
INTRODUCTION

5. Indiahasarichdiversityoflichens
representedbymorethan2000species,
(Awasthi;2000).Whichisabout10%of
thetotal20000speciesknownfromthe
world.Thelichensarecommonto
abundantintemperateandalpineregions
oftheHimalayasandhillyregionof
peninsularIndia.
•DISTRIBUTION

6. About Lichens
Symbiotic
Association
Algae
Fungi
Photobiont
Mycobiont
800
Total Known
Secondary
metabolites
50
Common
with other
Group of
Plants
700
Unique not
known in
any other
Group of
Plants
Lichen produce about 800 unique type of chemicals of which
only few are common with other group of plants and mostly
more than 700 are unique only known from lichens.

7. Morethan700lichenmetabolitesare
knownfromthelichensoutofwhichonly
50arecommonwithothergroupofplants,
650areuniquetolichensandnot
producedbyanyotherplantgroup.
Lichenmetabolitesexertawidevarietyof
biologicalactionincludingantibiotic,
antimicrobial,antibacterial,antiviral,anti-
inflammatory,analgesic,antipyretic,
atiproliferticandcytotoxiceffect
•Secondary Metabolites

8. GROWTH FORMS
FruticoseCrustose Foliose

9. •1.Crustose-Thallushavingcrustlike,growingtight
againstthesubstrate.
•Example:Acarospora,Lecanora
•2.Foliose-Thallushavingleafandlobelike,loosely
attachedwithsubstratethroughrhizoids,withflatsheets
oftissuenottightlybound.
•Example:Parmelia,Flavoparmelia
•3.Fruticose-Thallushavingribbon,threadlike,
free-standingbranchingtubes,sometimeperpendiculate
attachedwithsubstratum.
•Example:Usnea,Cladonia
•Lichens occur in three basic growth forms

10. TYPES OF LICHENS
ON THE BASIS OF
SUBSTRATUM
•Corticolous
•Ramicolous
•Saxicolous
•Terricolous
•Foliicolous
•Muscicolous

11. On the basis of substratum lichens may be grouped into
Corticolouslichens: If growing over bark of tree, cortex or
wood. Example : Heterodermia
Saxicolouslichens: Growing on rock boulder. Example :
Acarospora
Terricolouslichens: When growing on soil. Example :
Heterodermia
Foliicolouslichens: Grow on perrenialleaves.Example :
Strigula
Muscicolouslichens: If growing lichen on mosses.
Example : Peltigera
Ramicolouslichens: Some lichens only grow on the twigs
of the tree, is called ramicolouslichens. Example :
Ramalina
TYPES OF LICHENS ON THE BASIS OF SUBSTRATUM

12. ◊Food for man
◊Food for animals
◊Medicines
◊Dyes
◊In perfumery
◊Pioneer of
colonization
◊Indicators of air
pollution
ECONOMIC IMPORTANCE OF LICHENS

13. Forest area with dominant lichens

14. Forest area with dominant lichens